7 - Facial growth 2 Flashcards
1
Q
How does the mandible form?
A
Intramembranous ossification
2
Q
How does the maxilla form?
A
Intramembranous ossification
3
Q
Describe the neonatal face.
A
- face is smaller in comparison to the head
- eyes are large
- ears low set
- forehead is upright and bulbous
- short nose
4
Q
How does the skull develop?
A
- sutures
- synchondroses
- surface deposition
5
Q
What is a suture?
A
- fibrous joint between intramembranous bone
- band of connective tissue that has osteogenic cells which provide new bone growth
- growth happens in reaction to other structures applying force the bone and pulling the suture apart
- when growth is complete the sutures fuse
6
Q
What are synchondroses?
A
- cartilaginous plate pushes apart in two directions
- found in midline
- exist between ethmoid, sphenoid and occipital bones
- cartilage based growth occurs by bones on either side moving away
- new cartilage is formed in the centre of the synchondrosis whilst the outer cartilage turns to bone
7
Q
What is surface deposition?
A
- new bone is deposited on the periosteum of existing bone
- bones maintain shape by resorption occurring on the opposite surface
- known as remodelling
- the change in position is known as drift
8
Q
How does the vault grow?
A
- occurs until age 7, rate of growth greatest until age 3
- growth occurs at the sutures (intramembranous ossification) and via surface deposition
- surface deposition causes the vault to increase in size radially
9
Q
How does the cranial base grow?
A
- endochondral ossification and surface remodelling
- half the growth is completed by age 3 but continues until age 20
10
Q
What are the different synchondroses of the skull?
A
- spheno-ethmoidal
- spheno-occipital
11
Q
When does the spheno-ethmoidal synchondrosis fuse?
A
7 years
12
Q
When does the spheno-occipital synchondrosis fuse?
A
- CLOSES around 13-15 in females and 15-17 in males
- FUSES at around 20 years
13
Q
How does cranial base growth impact orthodontics?
A
- due to the anterior cranial base finishing growth at age 7, it can be used to superimpose lateral cephs to assess growth in other areas
- the angle and size of the cranial base affects the maxillary and mandibular relationship
14
Q
Describe the growth of the maxilla.
A
- follows neural growth pattern
- articulates with the anterior cranial base
- cranial base displaces displaces maxilla downwards and forwards
- this creates space for maxillary tuberosities and eruption of molar teeth
- sutural growth occurs at zygomatic and frontal bones, as well as the mid-palatine suture
- surface deposition on hard palate, alveolar process and nasal cavity
15
Q
Describe the growth of the mandible.
A
- downwards and forwards
- growth occurs at condylar cartilage and surface remodelling
- deposition of bone mainly posterior and laterally
- resorption of bone mainly at anterior and lingual surfaces
- height of ramus and length of dental arches increased
